Conveying apparatus

ABSTRACT

A conveying apparatus, including: a conveyor mechanism; a housing; a first tray configured to receive a medium conveyed by the conveyor mechanism; an image reader disposed above the first tray, wherein a first discharge opening for discharging the medium outside the housing is formed in an upper surface of the housing so as not to overlap the image reader when viewed from above, and wherein the conveying apparatus further includes: a switcher for switching a destination of the medium selectively between the first tray and the first discharge opening; and a tray unit removably mountable on the upper surface of the housing and including a first introduction opening opposed to the first discharge opening, a second conveyance path for conveying the medium passed the first discharge opening and the first introduction opening, and at least one second tray for receiving the medium conveyed through the second conveyance path.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent ApplicationNo. 2016-194007, which was filed on Sep. 30, 2016, the disclosure ofwhich is herein incorporated by reference in its entirety.

BACKGROUND Technical Field

The following disclosure relates to a conveying apparatus including: amain body having a receiving tray; an image reader; and an optional unithaving at least one optional receiving tray and configured to bemountable on and removable from the apparatus.

Description of Related Art

There has been known a technique of removably mounting, on a conveyingapparatus, an optional unit having at least one receiving tray. In aknown copying machine (conveying apparatus), for instance, an uprightportion including a conveyance path is mounted on one side of thecopying machine, and a sorter (optional unit) is removably mounted on anupper end portion of the upright portion.

SUMMARY

The known conveying apparatus in which the upright portion is mounted onone side of the apparatus and the optional unit is mounted on the upperend portion of the upright portion inevitably has a large footprintoccupied on the horizontal plane. In the known conveying apparatus, theupright portion is mounted on one side thereof such that the uprightportion is located at a height level higher than a lower surface of theconveying apparatus, and the optional unit is mounted on the upper endportion of the thus mounted upright portion. According to thisconfiguration, the center of gravity of the apparatus as a whole islocated outside a region occupied or taken up by the apparatus on thehorizontal plane, causing instability in posture of the apparatus as awhole and resulting in a risk that the apparatus falls over or topplesover.

Accordingly, an aspect of the disclosure relates to a conveyingapparatus having a construction in which an optional unit is removablymountable on the apparatus, the conveying apparatus obviating anincrease in a footprint of the apparatus as a whole on a horizontalplane and having a reduced risk of falling over or toppling over.

One aspect of the disclosure relates to a conveying apparatus including:a conveyor mechanism configured to convey a medium through a firstconveyance path; a housing that houses the conveyor mechanism; a firsttray configured to receive the medium conveyed by the conveyormechanism; an image reader disposed above the first tray, wherein afirst discharge opening is formed in an upper surface of the housing soas not to overlap the image reader when viewed from above, the mediumconveyed by the conveyor mechanism being discharged outside the housingfrom the first discharge opening, wherein the conveying apparatusfurther comprises: a switcher configured to switch a destination of themedium selectively between the first tray and the first dischargeopening; and a tray unit mountable on and removable from the uppersurface of the housing, the tray unit including a first introductionopening opposed to the first discharge opening, a second conveyance paththrough which the medium that has passed through the first dischargeopening and the first introduction opening is conveyed, and at least onesecond tray configured to receive the medium that has been conveyedthrough the second conveyance path.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features, advantages, and technical and industrialsignificance of the present disclosure will be better understood byreading the following detailed description of embodiments, whenconsidered in connection with the accompanying drawings, in which:

FIG. 1 is a schematic view of a printer according to a first embodiment;

FIG. 2 is a plan view of the printer of the first embodiment from whichan optional unit is removed;

FIG. 3A is a perspective view showing an outer side of respectiveright-side columns of a main body of the printer, an intermediate unit,and the optional unit in the printer of the first embodiment and FIG. 3Bis a perspective view showing an inner side of the right-side columns ofthe intermediate unit and the optional unit in the printer of the firstembodiment;

FIGS. 4A and 4B are perspective views showing an inner side ofrespective left-side columns of the main body, the intermediate unit,and the optional unit in the printer of the first embodiment, FIG. 4Ashowing a state in which a switcher is located at a position at whichthe switcher permits a sheet to be conveyed to a receiving tray of themain body, FIG. 4B showing a state in which the switcher is located at aposition at which the switcher permits the sheet to be conveyed to adischarge opening of the main body;

FIG. 5 is a schematic view of a printer according to a secondembodiment;

FIG. 6 is a schematic view showing a state in which a housing of ascanner unit is opened and closed in the printer of the secondembodiment;

FIG. 7 is a schematic view of a printer according to a third embodiment;

FIG. 8 is a schematic view of a printer according to a fourthembodiment; and

FIG. 9A is a perspective view showing an outer side of a right-sidecolumn of an intermediate unit of a printer according to a fifthembodiment and FIG. 9B is a perspective view of a right-side column ofan intermediate unit of a printer according to a sixth embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS First Embodiment

Referring first to FIG. 1, there will be explained an overall structureof a printer 1 according to a first embodiment of the presentdisclosure.

In the following explanation, a left side and a right side in FIG. 1 arerespectively defined as a front side and a rear side of the printer 1. Aside corresponding to a front surface of the drawing sheet of FIG. 1 anda side corresponding to a back surface of the drawing sheet of FIG. 1are respectively defined as a right side and a left side of the printer1. Further, an upper side and a lower side in FIG. 1 are respectivelydefined as an upper side and a lower side of the printer 1.

The printer 1 includes a main body 10, an intermediate unit 20, anoptional unit 30 (as one example of “tray unit”), and a scanner unit 40(as one example of “image reader”).

The main body 10 includes a housing 11, a storage tray 12, a conveyormechanism 13, an image former 14, a receiving tray 15 (as one example of“first tray”), and a controller 16. The storage tray 12 is provided at alower portion of the housing 11 and is capable of storing a plurality ofsheets (each as one example of “medium”) to be conveyed by the conveyormechanism 13. The receiving tray 15 is provided at an upper portion ofthe housing 11 and is capable of receiving the sheets that have beenconveyed by the conveyor mechanism 13. The controller 16 includes acentral processing unit (CPU), a read only memory (ROM), and a randomaccess memory (RAM) and controls devices of the printer 1 based on acommand sent from an external apparatus such as a personal computer (PC)connected to the printer 1.

The housing 11 has a generally rectangular parallelepiped shape andhouses the storage tray 12, the conveyor mechanism 13, the image former14, and the controller 16. The receiving tray 15 is constituted by anupper surface 11 a of the housing 11. A discharge opening 11 x, throughwhich the sheet conveyed by the conveyor mechanism 13 is dischargedoutside the housing 11, is formed in a region of the upper surface 11 aof the housing 11 in which the receiving tray 15 is not provided,namely, the discharge opening 11 x is located rearward of the receivingtray 15. A discharge opening 11 y, through which the sheet conveyed bythe conveyor mechanism 13 is discharged to the receiving tray 15, isformed at an upper portion of the housing 11 between the receiving tray15 and the discharge opening 11 x. The receiving tray 15 is disposeddownstream of the discharge opening 11 x in a movement direction D15 inwhich the sheet moves when received by the receiving tray 15. Themovement direction D15 is one example of “first direction”.

The conveyor mechanism 13 is configured to convey the sheet along a pathR10 formed in the housing 11 and includes conveyance rollers 13 a,guides 13 b, and a switcher 13 c. The path R10 includes a path R10 aextending from the storage tray 12 to the receiving tray 15 and a pathR10 b extending from the storage tray 12 to the discharge opening 11 x.The path R10 b is common, at its portion extending from the storage tray12 to a branch position Rx, to the path R10 a and branches off from thepath R10 a at the branch position Rx. The switcher 13 c is disposed atthe branch position Rx. The switcher 13 c is pivotable about a shaft 13ca extending in a right-left direction, so as to be movable between: aposition (indicated by the dashed line in FIG. 1) at which the switcherpermits the sheet to be conveyed to the receiving tray 15; and aposition (indicated by the solid line in FIG. 1) at which the switcher13 c permits the sheet to be conveyed to the discharge opening 11 x.That is, the conveyor mechanism 13 is configured to convey the sheetselectively to one of the receiving tray 15 and the discharge opening 11x.

The image former 14 includes a photoconductive drum 14 a, a transferroller 14 b, a charging unit 14 x, a laser unit 14 y, a toner unit 14 z,a fixing roller 14 c, and a pressure roller 14 d. The photoconductivedrum 14 a and the transfer roller 14 b are disposed upstream of thebranch position Rx in the path R10, so as to be in contact with eachother with the path R10 interposed therebetween. The fixing roller 14 cand the pressure roller 14 d are disposed upstream of the branchposition Rx in the path R10 and downstream of the photoconductive drum14 a and the transfer roller 14 b, so as to be in contact with eachother with the path R10 interposed therebetween.

The surface of the photoconductive drum 14 a is charged by the chargingunit 14 x and is irradiated with a laser light emitted from the laserunit 14 y, so as to form an electrostatic latent image on the surface.Further, toner is applied to the surface from the toner unit 14 z, so asto form a toner image. The transfer roller 14 b, to which is applied avoltage opposite to a voltage applied to the photoconductive drum 14 a,transfers the toner image to the sheet nipped by the photoconductivedrum 14 a and the transfer roller 14 b. Subsequently, toner is fixed onthe sheet by the heat of the fixing roller 14 c and the pressure of thefixing roller 14 c and the pressure roller 14 d. Thus, an image isformed on the sheet by the image former 14.

The intermediate unit 20 includes a housing 21 and conveyance rollers22.

The housing 21 is mountable on and removable from the upper surface 11 aof the housing 11 and houses the conveyance rollers 22. An introductionopening 21 x corresponding to the discharge opening 11 x is formed in alower surface 21 b of the housing 21. A discharge opening 21 y thatcommunicates with the introduction opening 21 x is formed in an uppersurface 21 a of the housing 21. There is formed, in the housing 21, apath R20 through which the sheet is conveyed from the introductionopening 21 x to the discharge opening 21 y. In the present embodiment,the path R20 linearly extends in the vertical direction. Theintroduction opening 21 x and the discharge opening 21 y are arranged inthe vertical direction so as to align with each other as seen in thevertical direction.

The conveyance rollers 22 convey the sheet along the path R20. Two pairsof the conveyance rollers 22 are disposed along the path R20 so as to bespaced apart from each other. The conveyance rollers 22 of each pair arein contact with each other with the path R20 interposed therebetween.

The optional unit 30 includes a housing 31, conveyance rollers 32, andfour receiving trays 35.

The housing 31 is mountable on and removable from the upper surface 21 aof the housing 21 and houses the conveyance rollers 32. (The housing 31is mountable on and removable from the upper surface 11 a of the housing11 in an instance where the intermediate unit 20 is not provided.) Anintroduction opening 31 x (as one example of “first introductionopening”) corresponding to the discharge opening 21 y is formed in alower surface 31 a of the housing 31. (The introduction opening 31 xcorresponds to the discharge opening 11 x in an instance where thehousing 31 is mounted on the upper surface 11 a of the housing 11.)There is formed, in the housing 31, a path R30 (as one example of“second conveyance path”) through which the sheet is conveyed from theintroduction opening 31 x to each receiving tray 35 (as one example of“second tray”). The path R30 includes: a path extending to an uppermostone of the four receiving trays 35; and three paths that branch off fromthe path at respective three branch positions, so as to respectivelyextend to the three receiving trays 35 disposed below the uppermostreceiving tray 35. Switchers 33 c similar to the switcher 13 c areprovided at the respective three branch positions. Each switcher 33 c ispivotable about a corresponding shaft 33 ca that extends in theright-left direction, so as to be movable between: a position (indicatedby the dashed line in FIG. 1) at which the switcher 33 c permits thesheet to be conveyed to the corresponding receiving tray 35; and aposition (indicated by the solid line in FIG. 1) at which the switcher33 c permits the sheet to be conveyed upward. In an instance where theintermediate unit 20 is provided in the printer 1 as shown in FIG. 1,the housing 11 and the housing 21 are one example of “housing”, thepaths R10 and R20 are one example of “first conveyance path”, thedischarge opening 21 y is one example of “first discharge opening”, thedischarge opening 11 x is one example of “second discharge opening”, thepath R10 is one example of “third conveyance path”, the path R20 is oneexample of “fourth conveyance path”, and the introduction opening 21 xis one example of “second introduction opening”. On the other hand, inan instance where the intermediate unit 20 is not provided in theprinter 1, the housing 11 is one example of “housing”, the path R10 isone example of “first conveyance path”, and the discharge opening 11 xis one example of “first discharge opening”.

The four receiving trays 35 are arranged in the vertical direction. Thefour receiving trays 35 are supported at respective proximal portions bythe housing 31 and protrude from the housing 31 forward and obliquelyupward. A movement direction D35 in which the sheet moves when receivedby each receiving tray 35 is the same as the movement direction D15.That is, the movement direction D35 is a direction from the rear sidetoward the front side.

The scanner unit 40 is configured to read an image on the sheet. Thescanner unit 40 is supported by the intermediate unit 20 and is disposedat a front portion of the upper surface 21 a of the housing 21. Thescanner unit 40 is disposed at the front portion of the upper surface 21a of the housing 21, and the discharge opening 21 y is formed at a rearportion of the upper surface 21 a of the housing 21 which is outside aregion of the upper surface 21 a in which the scanner unit 40 isdisposed. That is, the scanner unit 40 is disposed downstream of thedischarge opening 21 y in the movement direction D15, D35. In otherwords, the discharge opening 21 y is formed in the upper surface 21 a ofthe housing 21 so as not to overlap the scanner unit 40 when viewed fromabove. The scanner unit 40 includes a cover 41 (as one example of“opening and closing member”) configured to be openable about a shaft 41a located on the upstream side in the movement direction D15, D35 so asto extend in the right-left direction. The cover 41 is disposed belowthe receiving trays 35.

The scanner unit 40 is disposed below the receiving trays 35 and abovethe receiving tray 15. That is, the receiving tray 15, the scanner unit40, and the receiving trays 35 are disposed in this order from thebottom. Respective projective regions obtained by projecting, in thevertical direction, the receiving tray 15, the scanner unit 40, and thereceiving trays 35 onto an imaginary plane orthogonal to the verticaldirection at least partially overlap one another. In other words, thefour receiving trays 35 are disposed so as to overlap the scanner unit40 when viewed from above, as shown in FIG. 1. The intermediate unit 20has a length H20 in a height direction smaller than a length H30 of theoptional unit 30 in the height direction.

Referring next to FIGS. 2-4, the main body 10, the intermediate unit 20,and the optional unit 30 will be explained in detail.

The intermediate unit 20 includes a pair of columns 21L, 21R whichextend in the vertical direction and which are opposed to and spacedapart from each other in the right-left direction. The optional unit 30includes a pair of columns 31L, 31R which extend in the verticaldirection and which are opposed to and spaced apart from each other inthe right-left direction. The main body 10 includes a pair of columns11L, 11R which extend in the vertical direction and which are opposed toand spaced apart from each other in the right-left direction. Thecolumns 11L, 11R, the columns 21L, 21R, and the columns 31L, 31R arearranged in the vertical direction in this order from the bottom. Thecolumns 11L, 11R are fixed to the housing 11, the columns 21L, 21R arefixed to the housing 21, and the columns 31L, 31R are fixed to thehousing 31. Each of the columns 11L, 11R, 21L, 21R, 31L, 31R has anH-shaped cross section taken along a plane orthogonal to the verticaldirection.

Metal members 17, 27, 37 are respectively attached to outer surfaces ofthe columns 11L, 11R, outer surfaces of the columns 21L, 21R, and outersurfaces of the columns 31L, 31R. Specifically, the metal member 17 isattached to the outer surface of each column 11L, 11R. While only themetal member 17 attached to the outer surface of the right-side column11R is illustrated in FIG. 3A, the metal member 17 is similarly attachedto the outer surface of the left-side column 11L. The metal member 27 isattached to the outer surface of each column 21L, 21R. While only themetal member 27 attached to the outer surface of the right-side column21R is illustrated in FIG. 3A, the metal member 27 is similarly attachedto the left-side column 21L. The metal member 37 is attached to theouter surface of each column 31L, 31R. While only the metal member 37attached to the outer surface of the right-side column 31R isillustrated in FIG. 3A, the metal member 37 is similarly attached to theouter surface of the left-side column 31L. The metal member 17, 27, 37of one unit functions as a connector by which the one unit is connectedto another unit.

The metal member 17 functions as a connector of the main body 10 bywhich the main body 10 is connected to the intermediate unit 20 or theoptional unit 30. The metal member 17 includes: a base portion 17 xshaped like a plate and extending in the vertical direction; and aprotruding portion 17 y protruding from the base portion 17 x outward ofthe column 11L, 11R in the right-left direction. The base portion 17 xis provided with a protrusion 17 x 1 for positioning the intermediateunit 20 or the optional unit 30 with respect to the main body 10 in thevertical direction. The protruding portion 17 y has a through-hole 17 y1 into which an insertion portion 27 b of the metal member 27 or themetal member 37 is insertable. The through-hole 17 y 1 is formed throughthe protruding portion 17 y in the vertical direction.

The metal member 37 shaped like a plate and extending in the verticaldirection functions as a connector of the optional unit 30 by which theoptional unit 30 is connected to the intermediate unit 20 or the mainbody 10.

The metal member 27 includes: a receiver portion 27 a functioning as aconnector of the intermediate unit 20 by which the intermediate unit 20is connected to the optional unit 30; and the insertion portion 27 bfunctioning as a connector of the intermediate unit 20 by which theintermediate unit 20 is connected to the main body 10.

The receiver portion 27 a is similar to the metal member 17 inconstruction. That is, the receiver portion 27 a includes: a baseportion 27 x shaped like a plate and extending in the verticaldirection; and a protruding portion 27 y protruding from the baseportion 27 x outward of the column 21L, 21R in the right-left direction.The base portion 27 x is provided with a protrusion 27 x 1 forpositioning the optional unit 30 with respect to the intermediate unit20 in the vertical direction. The protruding portion 27 y has athrough-hole 27 y 1 into which the metal member 37 is insertable. Thethrough-hole 27 y 1 is formed through the protruding portion 27 y in thevertical direction.

The insertion portion 27 b is similar to the metal member 37 inconstruction. That is, the insertion portion 27 b is shaped like a plateand extends in the vertical direction.

The receiver portion 27 a is fixed to the column 21L, 21R such that alower end of the base portion 27 x is inserted onto a pair ofprotrusions 21 p provided on the outer surface of the column 21L, 21R.The insertion portion 27 b is fixed to the column 21L, 21R such that anupper end of the insertion portion 27 b is inserted onto the pair ofprotrusions 21 p. The receiver portion 27 a and the insertion portion 27b are fixed relative to each other through the pair of protrusions 21 p.

The base portion 27 x of the receiver portion 27 a is in contact withthe outer surface of the column 21L, 21R. The insertion portion 27 b isin contact with an outer surface of the lower end of the base portion 27x and an outer surface of a plate 27 c which is fixed to the outersurface of the column 21L, 21R below the base portion 27 x. Thus, aclearance is defined between the insertion portion 27 b and the outersurface of the column 21L, 21R. The plate 27 c has the same thickness asthe base portion 27 x. In other words, a projective region obtained byprojecting the insertion portion 27 b in the vertical direction onto theimaginary plane orthogonal to the vertical direction and a projectiveregion obtained by projecting the base portion 27 x of the receiverportion 27 a in the vertical direction onto the imaginary plane do notcoincide with each other but are adjacent to each other.

Like the insertion portion 27 b, the metal member 37 is fixed to theouter surface of the column 31L, 31R via a plate (not shown) having thesame thickness as the base portion 27 x. Thus, a clearance is definedbetween the metal member 37 and the outer surface of the column 31L,31R.

The base portion 17 x and the protruding portion 17 y of the metalmember 17 are disposed so as to respectively align with the base portion27 x and the protruding portion 27 y of the receiver portion 27 a asseen in the vertical direction. The metal member 37 is disposed so as toalign with the insertion portion 27 b as seen in the vertical direction.In other words, a projective region obtained by projecting, in thevertical direction, the insertion portion 27 b functioning as theconnector of the intermediate unit 20 connecting the intermediate unit20 to the main body 10 onto the imaginary plane orthogonal to thevertical direction coincides with a projective region obtained byprojecting, in the vertical direction, the metal member 37 functioningas the connector of the optional unit 30 connecting the optional unit 30to the intermediate unit 20 onto the imaginary plane. Further, aprojective region obtained by projecting, in the vertical direction, thereceiver portion 27 a functioning as the connector of the intermediateunit 20 connecting the intermediate unit 20 to the optional unit 30 ontothe imaginary plane coincides with a projective region obtained byprojecting, in the vertical direction, the metal member 17 functioningas the connector of the main body 10 connecting the main body 10 to theintermediate unit 20 onto the imaginary plane.

With the configurations of the metal members 17, 27, 37 described above,the optional unit 30 is mountable on and removable from the uppersurface 21 a of the intermediate unit 20. In an instance where theintermediate unit 20 is not provided in the printer 1, the optional unit30 is mountable on and removable from the upper surface 11 a of thehousing 11 (the main body 10).

In an inner space sandwiched by the pair of columns 21L, 21R and thepair of columns 31L, 31R in the right-left direction, there aredisposed: the conveyance rollers 22, 32; a motor 38 shown in FIGS. 2 and3B for driving the conveyance rollers 22, 32; connectors 18, 28; cables18 c, 28 c; gears (transmission mechanism) for transmitting a driveforce of the motor 38 to the conveyance rollers 22, 32; a solenoid 39 s(drive member) shown in FIGS. 4A and 4B for moving the switcher 13 c;and a transmission member 29 d. While only the conveyance rollers 22 areillustrated in FIG. 2, the conveyance rollers 32 are disposed so as toalign with the conveyance rollers 22 as seen in the vertical direction.While only one gear 23 is illustrated in FIG. 2, a plurality of gearsare disposed. The transmission member 29 d is connected to both of theswitcher 13 c and the solenoid 39 s and is movable in the verticaldirection so as to transmit a drive force of the solenoid 39 s to theswitcher 13 c.

As shown in FIG. 2, a projective point G38 obtained by projecting acenter of gravity of the motor 38 in the vertical direction onto theimaginary plane orthogonal to the vertical direction, a projective pointG20 obtained by projecting a center of gravity of the intermediate unit20 in the vertical direction onto the imaginary plane, and a projectivepoint G obtained by projecting a center of gravity of a portionconstituted by the intermediate unit 20 and the optional unit 30 in thevertical direction onto the imaginary plane are located within aprojective region 11A obtained by projecting the housing 11 in thevertical direction onto the imaginary plane.

As shown in FIG. 3B, the motor 38 is attached to a lower end of an innersurface of the column 31R. The connector 28 is attached to an upper endof an inner surface of the column 21R. When the optional unit 30 ismounted on the intermediate unit 20, the connector 28 is connected toterminals of the motor 38. The cable 28 c extends downward from theconnector 28 along the inner surface of the column 21R. The connector 18is attached to an upper end of an inner surface of the column 11R. Whenthe intermediate unit 20 is mounted on the main body 10, the connector18 is connected to a lower end of the cable 28 c. When the optional unit30 is mounted on the main body 10, the connector 18 is connected to theterminals of the motor 38. The cable 18 c extends downward from theconnector 18 along the inner surface of the column 11R so as to beconnected to the controller 16.

As shown in FIGS. 4A and 4B, the solenoid 39 s is attached to a lowerend of an inner surface of the column 31L. At the lower end of the innersurface of the column 31L, there are provided: a pivot member 39 apivotable about a shaft 39 ax that extends in the right-left direction;a spring 39 b contacting a distal end of an arm 39 a 1 which is one oftwo arms of the pivot member 39 a; a transmission member 39 d engagingwith an arm 39 a 2 which is the other of the two arms of the pivotmember 39 a; and a stopper 39 c. The arm 39 a 1 is held in engagementwith a plunger of the solenoid 39 s. The transmission member 39 dextends in the vertical direction and comes into contact with an upperend of the transmission member 29 d when the optional unit 30 is mountedon the intermediate unit 20. The spring 39 b biases the pivot member 39a in a direction in which the transmission member 39 d moves upward. Thestopper 39 c limits an upward movement of the transmission member 39 dwhen it comes into contact with the arm 39 a 2.

The transmission member 29 d is attached to the inner surface of thecolumn 21L and extends in the vertical direction along the innersurface. The transmission member 29 d has the same length in thevertical direction as the column 21L. On the inner surface of the column21L, there are provided: a pivot member 29 a pivotable about a shaft 29ax that extends in the right-left direction; a spring 29 b contacting adistal end of an arm 29 a 1 which is one of two arms of the pivot member29 a; and a stopper 29 c. An arm 29 a 2, which is the other of the twoarms of the pivot member 29 a, is held in engagement with thetransmission member 29 d. The spring 29 b biases the pivot member 29 ain a direction in which the transmission member 29 d moves upward. Thestopper 29 c limits an upward movement of the transmission member 29 dwhen it comes into contact with a protrusion 29 d 1 formed on thesurface of the transmission member 29 d.

The switcher 13 c is attached to an upper end of the inner surface ofthe column 11L. At the upper end of the inner surface of the column 11L,there are provided: a pivot member 19 a pivotable about the shaft 13 ca;a spring 19 b contacting a distal end of an arm 19 a 1 which is one oftwo arms of the pivot member 19 a; a transmission member 19 d contactingan upper end of an arm 19 a 2 which is the other of the two arms of thepivot member 19 a; and a stopper 19 c. The pivot member 19 a is fixed toa proximal end of the shaft 13 ca and is configured to pivot so as torotate the shaft 13 ca for thereby pivoting the switcher 13 c. Thetransmission member 19 d extends in the vertical direction. When theintermediate unit 20 is mounted on the main body 10, the transmissionmember 19 d comes into contact with a lower end of the transmissionmember 29 d. When the optional unit 30 is mounted on the main body 10,the transmission member 19 d comes into contact with a lower end of thetransmission member 39 d. The spring 19 b biases the pivot member 19 ain a direction in which the transmission member 19 d moves upward. Thestopper 19 c limits an upward movement of the transmission member 19 dwhen it comes into contact with a protrusion 19 d 1 formed on thesurface of the transmission member 19 d.

When the solenoid 39 s is not driven, namely, when the transmissionmember 29 d does not transmit the drive force of the solenoid 39 s tothe switcher 13 c, the components described above are in a state shownin FIG. 4A. In this state, the lower end of the transmission member 39 dis located at the same height level as the lower end of the column 31L.Thus, the transmission member 39 d does not protrude downward from thelower surface 31 a of the housing 31. The upper end of the transmissionmember 29 d is located at the same height level as the upper end of thecolumn 21L while the lower end of the transmission member 29 d islocated at the same height level as the lower end of the column 21L.Thus, the transmission member 29 d does not protrude downward from thelower surface 21 b of the housing 21. The upper end of the transmissionember 19 d is located at the same height level as the upper end of thecolumn 11L. Thus, the transmission member 19 d is not retracted downwardfrom the upper surface 11 a of the housing 11.

When the solenoid 39 s is driven, namely, when the transmission member29 d transmits the drive force of the solenoid 39 s to the switcher 13c, the state of the components described above is changed to a stateshown in FIG. 4B. Specifically, the plunger of the solenoid 39 scontracts, so that the pivot member 39 a pivots against the biasingforce of the spring 39 b and the transmission member 39 d movesdownward. As a result, the transmission member 29 d moves downward bybeing pushed down by the transmission member 39 d, and the transmissionmember 19 d moves downward by being pushed down by the transmissionmember 29 d. In this instance, the downward movement of the transmissionmember 29 d causes the pivot member 29 a to pivot against the biasingforce of the spring 29 b, and the downward movement of the transmissionmember 19 d causes the pivot member 19 a to pivot against the biasingforce of the spring 19 b. As a result, the switcher 13 c moves from theposition (FIG. 4A) at which the switcher 13 c permits the sheet to beconveyed to the receiving tray 15 to the position (FIG. 4B) at which theswitcher 13 c permits the sheet to be conveyed to the discharge opening11 x. In this instance, the lower end of the transmission member 39 d islocated at a height level lower than the lower end of the column 31L.Thus, the transmission member 39 d protrudes downward from the lowersurface 31 a of the housing 31. The lower end of the transmission member29 d is located at a height level lower than the lower end of the column21L. Thus, the transmission member 39 d protrudes downward from thelower surface 21 b of the housing 21. The upper end of the transmissionmember 19 d is located at a height level lower than the upper end of thecolumn 11L. Thus, the transmission member 19 d is retracted downwardfrom the upper surface 11 a of the housing 11.

The present embodiment employs the configuration shown in FIG. 1 inwhich the scanner unit 40 is disposed on the upper surface of theintermediate unit 20, the discharge opening 21 y is formed outside theregion of the upper surface of the intermediate unit 20 in which thescanner unit 40 is disposed, and the optional unit 30 is mounted on theupper portion of the intermediate unit 20, instead of employing theconfiguration in which the upright portion is mounted on one side of themain body 10 and the intermediate unit 20 (the conveying apparatus), andthe optional unit 30 is mounted on the upper portion thereof. Theconfiguration according to the present embodiment prevents the footprintof the printer 1 as a whole on the horizontal plane from increasing andalso prevents the printer 1 from toppling over. Thus, the presentembodiment prevents, in the configuration in which the optional unit 30is removably mountable, the footprint of the printer 1 as a whole on thehorizontal plane from increasing and also prevents the printer 1 fromtoppling over.

The receiving tray 15 is disposed below the scanner unit 40. Further,the scanner unit 40 is disposed downstream of the discharge opening 21 yin the movement direction D15. For easy removal of the sheet, it isnatural to match the movement direction D15 in which the sheet moveswhen received by the receiving tray 15 and the movement direction D35 inwhich the sheet moves when received by each receiving tray 35 with eachother. In an instance where the movement directions D15, D35 are matchedwith each other, the configuration described above permits the receivingtrays 35, the scanner unit 40, and the receiving tray 15 to be arrangedin the vertical direction when the optional unit 30 is mounted on theintermediate unit 20, thereby ensuring a stabilized weight balance ofthe printer 1 as a whole and more effectively preventing the printer 1from toppling over.

The scanner unit 40 includes the cover 41 configured to be openableabout the shaft 41 a located on the upstream side in the movementdirection D15, so as to extend in the right-left direction (which isorthogonal to the movement direction D15 and the vertical direction). Itis thus possible to allow a user to take the sheet out of the receivingtray 15 (and the receiving trays 35) and to open and close the cover 41on the same side (the front side) of the printer 1, improving theworkability for the user.

The printer 1 includes the main body 10, the scanner unit 40, and theintermediate unit 20 which is mountable on and removable from the uppersurface of the main body 10. Further, the optional unit 30 is mountableon and removable from the upper surface of the intermediate unit 20. Inthis arrangement, the structure of the optional unit 30 is made commonfor various types of the main body 10, and the structure of theintermediate unit 20, i.e., the structure of the connector of theintermediate unit 20 connecting the intermediate unit 20 to the mainbody 10, is changed depending upon the types of the main body 10,thereby eliminating a need of developing the optional units 30 to beused exclusively for respective types of the main body 10 and resultingin a reduction of the cost of developing the optional unit 30.

The optional unit 30 includes the motor 38 (FIG. 3B) for driving theconveyance rollers 22 provided in the intermediate unit 20. In thisarrangement, the motor is provided in the optional unit 30 which is notrequired to be developed for various types of the main body 10 while themotor is not provided in the intermediate unit 20 which is required tobe developed for the respective types of the main body 10, therebyreducing a production cost of the intermediate unit 20 and reducing thecost of developing the printer 1 as a whole.

Second Embodiment

Referring next to FIGS. 5 and 6, there will be described a secondembodiment.

A printer 201 of the second embodiment and the printer 1 of the firstembodiment are different in the following configuration and areidentical in the other configuration. That is, the printer 201 differsfrom the printer 1 in that: the printer 201 includes a cover 50 in placeof the intermediate unit 20 and the optional unit 30; the scanner unit40 is disposed not on the upper surface of the intermediate unit 20 buton the upper surface of the main body 10; the scanner unit 40 which isconfigured such that the cover 41 is openable about the shaft 41 a isalso configured such that a housing 42 of the scanner unit 40 isopenable about a shaft 42 a located on the upstream side in the movementdirection D15 so as to extend in the right-left direction (which isorthogonal to the movement direction D15 and the vertical direction); asolenoid 11 s for moving the switcher 13 c is provided in the main body10; the image former 14 includes four photoconductive drums 14 a 1-14 a4 corresponding to respective four colors (CMYK) and the printer 201 isa color printer; and duplex printing on the sheet is performable.

In the second embodiment, a path R210 is formed in the housing 11, inaddition to the path R10. The path R210 is for conveying, again to theimage former 14, the sheet having the image formed on its first surface.

The image former 14 includes: the four photoconductive drums 14 a 1-14 a4; four transfer rollers 14 b 1-14 b 4; four charging units 14 x; thelaser unit 14 y; four toner units 14 z; the fixing roller 14 c; thepressure roller 14 d; and an intermediate transfer belt 14 e. Theintermediate transfer belt 14 e is in contact with a portion of the pathR10 on the upstream side of the branch position Rx in the path R10. Eachof the photoconductive drums 14 a 1-14 a 4 forms a pair with acorresponding one of the transfer rollers 14 b 1-14 b 4. Eachphotoconductive drum 14 a 1-14 a 4 and each transfer roller 14 b 1-14 b4 that form a pair are opposed to each other with the intermediatetransfer belt 14 e interposed therebetween. The four pairs are arrangedin a running direction of the intermediate transfer belt 14 e. Thefixing roller 14 c and the pressure roller 14 d are in contact with eachother with the path R10 interposed therebetween on the upstream side ofthe branch position Rx in the path R10 and on the downstream side of theintermediate transfer belt 14 e.

The surfaces of the photoconductive drums 14 a 1-14 a 4 are charged bythe respective charging units 14 x and are irradiated with a laser lightemitted from the laser unit 14 y, so that electrostatic latent imagesare formed on the respective surfaces. Subsequently, toner is suppliedto the surfaces from the respective toner units 14 z so as to form tonerimages thereon. The transfer rollers 14 b 1-14 b 4, to which is applieda voltage opposite to a voltage applied to the photoconductive drums 14a 1-14 a 4, transfer the toner images onto an outer surface of theintermediate transfer belt 14 e. Thereafter, the toner images aretransferred from the outer surface of the intermediate transfer belt 14e to the sheet, and toner is fixed on the sheet by the heat of thefixing roller 14 c and the pressure of the fixing roller 14 c and thepressure roller 14 d. Thus, a color image is formed on the sheet by theimage former 14.

The cover 50 is mountable on and removable from the upper surface 11 aof the housing 11 in a state in which the intermediate unit 20 and theoptional unit 30 are not mounted on the upper surface 11 a of thehousing 11. There is formed, in a lower surface 51 a of the cover 50, anintroduction opening 51 x (as one example of “third introductionopening”) corresponding to the discharge opening 11 x (the firstdischarge opening). There is formed, in the cover 50, a path R50 (as oneexample of “fifth conveyance path”) through which a sheet P is conveyedfrom the introduction opening 51 x.

The switcher 13 c is movable so as to be selectively located at: aposition at which the switcher 13 c permits the sheet to be conveyed tothe receiving tray 15; a position at which the switcher 13 c permits thesheet to be conveyed to the discharge opening 11 x; and a position atwhich the switcher 13 c permits the sheet, which has been conveyed tothe path R50 and the conveyance direction has been reversed, to beguided to the path R210.

The cover 50 includes a lower portion 51 at which the introductionopening 51 x is formed and an upper portion 52 pivotable about a shaft52 a that extends in the right-left direction. The upper portion 52includes a distal end 52 x contacting the upper surface of the cover 41.When the cover 41 opens and closes about the shaft 41 a and when thehousing 42 opens and closes about the shaft 42 a, the distal end 52 xkept in contact with the upper surface of the cover 41 pivots about theshaft 52 a.

When the controller 16 receives a command of single-sided printing, thecontroller 16 controls the conveyor mechanism 13 and the image former 14to convey the sheet P and form an image as described below.

The sheet P having an image formed on the first surface by the imageformer 14 is conveyed along the path R10 a and received by the receivingtray 15. Alternatively, the sheet P having an image formed on the firstsurface by the image former 14 is conveyed along the path R10 b,subsequently conveyed to the path R50 via the discharge opening 11 x andthe introduction opening 51 x, and finally discharged onto the cover 41.

When the controller 16 receives a command of duplex printing, thecontroller 16 controls the conveyor mechanism 13 and the image former 14to convey the sheet P and form an image as described below.

The sheet P having an image formed on the first surface by the imageformer 14 is conveyed along the path R10 b and is subsequently conveyedto the path R50 via the discharge opening 11 x and the introductionopening 51 x. The conveyance direction of the sheet P is reversed attiming when a leading end Px of the sheet P is located outside the cover50 and a trailing end Py thereof is located in the path R10 b on thedownstream side of the branch position Rx. Thereafter, the switcher 13 cis placed at the position at which the switcher 13 c permits the sheet Pto be conveyed to the path R210, so that the sheet P is conveyed againto the image former 14 along the path R210. After the image former 14forms an image on a second surface of the sheet P opposite to the firstsurface, the sheet P is received by the receiving tray 15 or by thereceiving tray 55 (as one example of “third tray”) of the cover 41.

The second embodiment described above offers the same advantages asthose offered by the first embodiment according to the sameconfiguration as employed in the first embodiment. The second embodimentfurther offers the following advantages.

Image formation on both surfaces of the sheet P and discharging of thesheet P onto the scanner unit 40 can be performed using the path R50provided in the cover 50.

The controller 16 controls the conveyor mechanism 13 and the imageformer 14 such that the sheet P, which has an image formed on the firstsurface by the image former 14, is conveyed to the path R50 via thedischarge opening 11 x and the introduction opening 51 x and issubsequently conveyed again to the image former 14 after the conveyancedirection of the sheet P has been reversed, so as to permit the imageformer 14 to form an image on the second surface of the sheet P. In thisinstance, image formation on both surfaces of the sheet P can beachieved using the path R50 provided in the cover 50.

Not only the cover 41 but also the housing 42 is openable. In thisarrangement, the user can take the sheet out of the receiving tray 15(and the receiving trays 55) and can open and close the cover 41 or thehousing 42, on the same side (the front side) of the printer 201,enhancing the workability for the user.

Third Embodiment

Referring next to FIG. 7, there will be described a third embodiment.

A printer 301 of the third embodiment and the printer 1 of the firstembodiment are different in the following configuration and areidentical in the other configuration. That is, the printer 301 differsfrom the printer 1 in the structure of the image former 14, namely, theprinter 301 is an LED printer including light sources 14 l 1-14 l 4 oflight emitting diodes (LED). Further, the printer 301 differs from theprinter 1 in the structure of the conveyor mechanism 13.

The conveyor mechanism 13 includes a loop-like conveyor belt 13 d inaddition to the conveyance rollers 13 a, the guide 13 b, and theswitcher 13 c. The conveyor belt 13 d conveys the sheet while supportingthe sheet below the four photoconductive drums 14 a 1-14 a 4.

The image former 14 includes the four photoconductive drums 14 a 1-14 a4, the four transfer rollers 14 b 1-14 b 4, the four charging units 14x, an LED unit 14 l, the four toner units 14 z, the fixing roller 14 c,and the pressure roller 14 d. The LED unit 14 l includes four lightsources 14 l 1-14 l 4. Each of the photoconductive drums 14 a 1-14 a 4forms a pair with a corresponding one of the transfer rollers 14 b 1-14b 4. Each photoconductive drum 14 a 1-14 a 4 and each transfer roller 14b 1-14 b 4 that form a pair are opposed to each other with the conveyorbelt 13 d interposed therebetween. The four pairs are arranged in therunning direction of the conveyor belt 13 d. The fixing roller 14 c andthe pressure roller 14 d are in contact with each other with the pathR10 interposed therebetween on the upstream side of the branch positionRx in the path R10 and on the downstream side of the conveyor belt 13 d.

The surfaces of the photoconductive drums 14 a 1-14 a 4 are charged bythe respective charging units 14 x and are irradiated with LED lightsemitted respectively from the light sources 14 l 1-14 l 4 of the LEDunit 14 l, so as to form electrostatic latent images. Subsequently,toner is supplied to the surfaces from the respective toner units 14 z,so as to form toner images. The transfer rollers 14 b 1-14 b 4, to whichis applied a voltage opposite to a voltage applied to thephotoconductive drums 14 a 1-14 a 4, transfer the toner images onto thesheet conveyed by the conveyor belt 13 d while being supported, andtoner is fixed on the sheet by the heat of the fixing roller 14 c andthe pressure of the fixing roller 14 c and the pressure roller 14 d.Thus, a color image is formed on the sheet by the image former 14.

The third embodiment described above offers the same advantages as thoseoffered by the first embodiment according to the same configuration asemployed in the first embodiment.

Fourth Embodiment

Referring next to FIG. 8, there will be described a fourth embodiment.

A printer 401 of the fourth embodiment and the printer 1 of the firstembodiment are different in the following configuration and areidentical in the other configuration. That is, the printer 401 differsfrom the printer 1 in the structure of the image former 14, namely, theprinter 401 is a line ink-jet printer having a line ink-jet head 14 i.Further, the printer 401 differs from the printer 1 in the structure ofthe conveyor mechanism 13.

The conveyor mechanism 13 includes the loop-like conveyor belt 13 d, inaddition to the conveyance rollers 13 a, the guide 13 b, and theswitcher 13 c.

The image former 14 includes the ink-jet head 14 i and an ink tank 14 t.The ink-jet head 14 i is held in communication with the ink tank 14 t.There are formed, in the ink-jet head 14 i, a reservoir for storing inksupplied from the ink tank 14 t and ink passages which branch off fromthe reservoir toward a plurality of ejection openings. The ejectionopenings are open to a lower surface 14 ix of the ink-jet head 14 i. Apredetermined spacing is formed between the lower surface 14 ix of theink-jet head 14 i and the upper surface of the conveyor belt 13 d.

Ink is ejected selectively from the ejection openings of the ink-jethead 14 i to the sheet conveyed by the conveyor belt 13 d while beingsupported, so that ink is attached onto the sheet. Thus, the imageformer 14 forms an image on the sheet.

The fourth embodiment described above offers the same advantages asthose offered by the first embodiment according to the sameconfiguration as employed in the first embodiment.

Fifth Embodiment

Referring next to FIG. 9A, there will be described a fifth embodiment.

A printer of the fifth embodiment and the printer 1 of the firstembodiment are different in the structure of the metal member of theintermediate unit 20 and are identical in the other configuration.

In the fifth embodiment, a metal member 527 of the intermediate unit 20includes a receiver portion 527 a and an insertion portion 527 b whichare not fixed relative to each other but are separated away from eachother. The receiver portion 527 a and the insertion portion 527 b arefixed to the column 21L, 21R independently of each other. The receiverportion 527 a is fixed to the column 21L, 21R such that the lower end ofthe base portion 27 x is inserted onto a pair of protrusions 521 p 1provided on the outer surface of the column 21L, 21R. The insertionportion 527 b is fixed to the column 21L, 21R such that its upper end isinserted onto a pair of protrusions 521 p 2 provided on the outersurface of the plate 27 c.

The base portion 27 x of the receiver portion 527 a is in contact withthe outer surface of the column 21L, 21R. The insertion portion 527 b isin contact with the outer surface of the plate 27 c. Also in the presentembodiment, a projective region obtained by projecting the insertionportion 527 b in the vertical direction onto the imaginary planeorthogonal to the vertical direction and a projective region obtained byprojecting the base portion 27 x of the receiver portion 527 a in thevertical direction onto the imaginary plane do not coincide with eachother but are adjacent to each other.

The fifth embodiment described above offers the same advantages as thoseoffered by the first embodiment according to the same configuration asemployed in the first embodiment. Further, the metal member of theintermediate unit 20 has a smaller size as compared with that in thefirst embodiment, resulting in a reduced cost for the metal member ofthe intermediate unit 20.

Sixth Embodiment

Referring next to FIG. 9B, there will be described a sixth embodiment.

A printer of the sixth embodiment and the printer 1 of the firstembodiment are different in the structure of the metal member of theintermediate unit 20 and are identical in the other configuration.

In the sixth embodiment, a metal member 627 of the intermediate unit 20includes a receiver portion 627 a and an insertion portion 627 b formedintegrally with each other. The metal member 627 is fixed to the column21L, 21R such that the insertion portion 627 b is inserted onto a pairof protrusions 621 p provided on the outer surface of the plate 27 c.

The base portion 27 x of the receiver portion 627 a is in contact withthe outer surface of the column 21L, 21R. The insertion portion 627 b isin contact with the outer surface of the plate 27 c. Also in the presentembodiment, a projective region obtained by projecting the insertionportion 627 b in the vertical direction onto the imaginary planeorthogonal to the vertical direction and a projective region obtained byprojecting the base portion 27 x of the receiver portion 627 a in thevertical direction onto the imaginary plane do not coincide with eachother but are adjacent to each other.

The sixth embodiment described above offers the same advantages as thoseoffered by the first embodiment according to the same configuration asemployed in the first embodiment. Further, the metal member of theintermediate unit 20 has a reduced number of components as compared withthe first embodiment, facilitating attaching of the metal member of theintermediate unit 20 to the column.

While the embodiments have been described above, it is to be understoodthat the disclosure is not limited to the details of the illustratedembodiments, but may be modified with various changes and modifications,which may occur to those skilled in the art, without departing from inthe spirit and scope of the disclosure.

The number of first trays and the number of second trays are optional.For instance, the main body may include a plurality of first trays whilethe tray unit may include one second tray. The number of conveyancerollers provided in the intermediate unit is not limited to four, butmay be any optional number equal to or larger than one. Alternatively,no conveyance rollers may be provided in the intermediate unit. Themotor for driving the conveyance rollers of the intermediate unit may beprovided in the intermediate unit instead of in the tray unit. The firstdischarge opening of the intermediate unit may be located upstream ordownstream of the second introduction opening of the intermediate unitin the first direction (the movement direction) in which the mediummoves when received by the second tray.

It is not necessarily required for the image reader to include theopening and closing member. The structure of the drive member for movingthe switcher and the structure of the transmission member fortransmitting the drive force of the drive member to the switcher may bechanged. For instance, the drive member and the transmission member maybe provided for the intermediate unit or the main body instead of forthe tray unit. The motor and the transmission mechanism may be disposedin outer spaces located outside the pairs of columns. The connectors maybe disposed in the inner space sandwiched by the pairs of columns. It isnot necessarily required for each of the intermediate unit and the trayunit to include the pair of columns. The structure of each connector maybe changed. The tray unit may be configured not to be removablymountable on the upper surface of the main body.

The projective point obtained by projecting the center of gravity of themotor in the vertical direction onto the imaginary plane orthogonal tothe vertical direction, the projective point obtained by projecting thecenter of gravity of the intermediate unit in the vertical directiononto the imaginary plane, and the projective point obtained byprojecting the center of gravity of the portion constituted by theintermediate unit and the tray unit in the vertical direction onto theimaginary plane are not necessarily required to be located within theprojective region obtained by projecting the main body in the verticaldirection onto the imaginary plane.

The present disclosure is applicable not only to the printer but also toa facsimile, a copying machine, a multi-function peripheral (MFP), andthe like. Also, the present disclosure is applicable not only to thelaser image forming apparatus but also to an ink-jet image formingapparatus and a thermal image forming apparatus. The present disclosureis applicable not only to the image forming apparatus but also todevices not equipped with the image former that includes thephotoconductive drum, the ink-jet head, and the like, namely, devicesconfigured not to perform image formation on the medium. The medium isnot limited to the sheet but may be a cloth or the like.

What is claimed is:
 1. A conveying apparatus, comprising: a conveyormechanism configured to convey a medium through a first conveyance path;a housing that houses the conveyor mechanism; a first tray configured toreceive the medium conveyed by the conveyor mechanism; an image readerdisposed above the first tray, wherein a first discharge opening isformed in an upper surface of the housing so as not to overlap the imagereader when viewed from above, the medium conveyed by the conveyormechanism being discharged outside the housing from the first dischargeopening, wherein the conveying apparatus further comprises: a switcherconfigured to switch a destination of the medium selectively between thefirst tray and the first discharge opening; and a tray unit mountable onand removable from the upper surface of the housing, the tray unitincluding (a) a path-defining housing which is disposed so as not tooverlap the image reader when viewed from above and which includes afirst introduction opening formed in a lower surface of thepath-defining housing so as to be opposed to the first discharge openingand (b) at least one second tray, the path-defining housing defining asecond conveyance path through which the medium that has passed throughthe first discharge opening and the first introduction opening isconveyed, the at least one second tray being configured to receive themedium that has been conveyed through the second conveyance path.
 2. Theconveying apparatus according to claim 1, wherein the first introductionopening is formed in a lower surface of the tray unit.
 3. The conveyingapparatus according to claim 1, wherein the at least one second tray isdisposed so as to overlap the image reader when viewed from above. 4.The conveying apparatus according to claim 1, wherein the housingincludes: a first housing in which is formed a third conveyance path asa part of the first conveyance path; and a second housing in which isformed a fourth conveyance path as a part of the first conveyance pathand which is disposed above the first housing, the first dischargeopening being formed in an upper surface of the second housing as theupper surface of the housing, and wherein the tray unit is mountable onand removable from the upper surface of the second housing as the uppersurface of the housing.
 5. The conveying apparatus according to claim 4,wherein a second discharge opening is formed in an upper surface of thefirst housing, the medium that has been conveyed through the thirdconveyance path being discharged from the second discharge opening, andwherein a second introduction opening is formed in a lower surface ofthe second housing so as to be opposed to the second discharge opening.6. The conveying apparatus according to claim 4, wherein the secondhousing includes at least one conveyance roller configured to convey themedium through the fourth conveyance path, and wherein the tray unitincludes a motor for driving the at least one conveyance roller.
 7. Theconveying apparatus according to claim 1, wherein the image reader isdisposed downstream of the first discharge opening in a first directionin which the medium moves when received by the first tray.
 8. Theconveying apparatus according to claim 7, wherein the image readerincludes an opening and closing member configured to be openable about ashaft which is located on an upstream side in the first direction so asto extend in a direction orthogonal to the first direction and avertical direction.
 9. The conveying apparatus according to claim 1,further comprising a cover mountable on and removable from the uppersurface of the housing when the tray unit is not mounted on the uppersurface of the housing, the cover including a third introduction openingopposed to the first discharge opening, a fifth conveyance path throughwhich the medium that has passed through the first discharge opening andthe third introduction opening is conveyed, and a third tray configuredto receive the medium that has been conveyed through the fifthconveyance path.
 10. The conveying apparatus according to claim 9,wherein the third introduction opening is formed in a lower surface ofthe cover.
 11. The conveying apparatus according to claim 9, furthercomprising: an image former configured to form an image on each of afirst surface of the medium and a second surface of the medium that isopposite to the first surface; and a controller configured to controlthe conveyor mechanism and the image former such that the medium, whichhas the image formed on the first surface by the image former, isconveyed to the fifth conveyance path via the first discharge openingand the third introduction opening and is subsequently conveyed again tothe image former after a conveyance direction of the medium has beenreversed, so as to permit the image former to form the image on thesecond surface of the medium.
 12. A conveying apparatus, comprising: aconveyor mechanism configured to convey a medium through a firstconveyance path; a housing that houses the conveyor mechanism; a firsttray configured to receive the medium conveyed by the conveyormechanism; an image reader disposed above the first tray, wherein afirst discharge opening is formed in an upper surface of the housing soas not to overlap the image reader when viewed from above, the mediumconveyed by the conveyor mechanism being discharged outside the housingfrom the first discharge opening, wherein the conveying apparatusfurther comprises: a switcher configured to switch a destination of themedium selectively between the first tray and the first dischargeopening; and a tray unit mountable on and removable from the uppersurface of the housing, the tray unit including a first introductionopening opposed to the first discharge opening, a second conveyance paththrough which the medium that has passed through the first dischargeopening and the first introduction opening is conveyed, and at least onesecond tray configured to receive the medium that has been conveyedthrough the second conveyance path, wherein the housing includes: afirst housing in which is formed a third conveyance path as a part ofthe first conveyance path; and a second housing in which is formed afourth conveyance path as a part of the first conveyance path and whichis disposed above the first housing, the first discharge opening beingformed in an upper surface of the second housing as the upper surface ofthe housing, and wherein the tray unit is mountable on and removablefrom the upper surface of the second housing as the upper surface of thehousing.
 13. The conveying apparatus according to claim 12, wherein asecond discharge opening is formed in an upper surface of the firsthousing, the medium that has been conveyed through the third conveyancepath being discharged from the second discharge opening, and wherein asecond introduction opening is formed in a lower surface of the secondhousing so as to be opposed to the second discharge opening.
 14. Theconveying apparatus according to claim 12, wherein the second housingincludes at least one conveyance roller configured to convey the mediumthrough the fourth conveyance path, and wherein the tray unit includes amotor for driving the at least one conveyance roller.
 15. A conveyingapparatus, comprising: a conveyor mechanism configured to convey amedium through a first conveyance path; a housing that houses theconveyor mechanism; a first tray configured to receive the mediumconveyed by the conveyor mechanism; an image reader disposed above thefirst tray, wherein a first discharge opening is formed in an uppersurface of the housing so as not to overlap the image reader when viewedfrom above, the medium conveyed by the conveyor mechanism beingdischarged outside the housing from the first discharge opening, whereinthe conveying apparatus further comprises: a switcher configured toswitch a destination of the medium selectively between the first trayand the first discharge opening; a tray unit mountable on and removablefrom the upper surface of the housing, the tray unit including a firstintroduction opening opposed to the first discharge opening, a secondconveyance path through which the medium that has passed through thefirst discharge opening and the first introduction opening is conveyed,and at least one second tray configured to receive the medium that hasbeen conveyed through the second conveyance path; and a cover mountableon and removable from the upper surface of the housing when the trayunit is not mounted on the upper surface of the housing, the coverincluding a third introduction opening opposed to the first dischargeopening, a fifth conveyance path through which the medium that haspassed through the first discharge opening and the third introductionopening is conveyed, and a third tray configured to receive the mediumthat has been conveyed through the fifth conveyance path.
 16. Theconveying apparatus according to claim 15, wherein the thirdintroduction opening is formed in a lower surface of the cover.
 17. Theconveying apparatus according to claim 15, further comprising: an imageformer configured to form an image on each of a first surface of themedium and a second surface of the medium that is opposite to the firstsurface; and a controller configured to control the conveyor mechanismand the image former such that the medium, which has the image formed onthe first surface by the image former, is conveyed to the fifthconveyance path via the first discharge opening and the thirdintroduction opening and is subsequently conveyed again to the imageformer after a conveyance direction of the medium has been reversed, soas to permit the image former to form the image on the second surface ofthe medium.